title: Multiple immunoglobulin heavy-chain gene transcripts in Abelson murine leukemia virus-transformed lymphoid cell lines.
abstract: Lymphoid cells transformed by Abelson murine leukemia virus (A-MuLV) contain three classes of RNA transcripts from immunoglobulin mu genes. P mu-mRNAs (productive) correspond to the normal 2.7-kilobase (kb) membrane (mu m) and 2.4-kb secreted (mu s) mu mRNA species both in size and coding capacity and occur at approximately equal abundance in most mu-positive (pre-B-like) A-MuLV transformants. A mu-mRNAs (aberrant) generally fall into one of two categories--aberrantly small 2.3-kb mu m and 2.0-kb mu s mRNAs which encode aberrantly small mu polypeptide chains, or normal-sized, V H-containing mu RNAs which do not encode immunologically identifiable mu polypeptide chains. In one case, the latter type of A mu-mRNA was demonstrated to result from an in-phase termination codon in the D segment of the mu mRNA. Also, most, if not all, A-MuLV transformants express members of a 3.0 to 1.9-kb set of C mu-containing, but V H-negative S mu-RNAs (for sterile), the expression of which may occur simultaneously with but independently of P mu-mRNAs or A mu-mRNAs. The S mu-RNA sequences do not encode immunologically identifiable mu chains and can be produced by cells with unrearranged heavy-chain alleles, such as T-lymphocytes, although the structure of the S mu-RNAs from T-lymphoid cells appears to be different from that of B-lymphoid cell S mu-RNAs. Certain A-MuLV transformants also express gamma-RNA sequences that are probably analogous to the three different forms of mu RNA. These data support the concept that heavy-chain allelic exclusion, like that of light chains, is not mediated by control at the DNA or RNA levels but is probably a consequence of feedback control from cytoplasmic mu chains.
mesh_terms: D000011:Abelson murine leukemia virus; D000818:Animals; D001483:Base Sequence; D002460:Cell Line; D002472:Cell Transformation, Viral; D003001:Cloning, Molecular; D004274:DNA, Recombinant; D005786:Gene Expression Regulation; D007143:Immunoglobulin Heavy Chains / Q000235:genetics*; D007148:Immunoglobulin mu-Chains / Q000235:genetics*; D008214:Lymphocytes / Q000276:immunology / Q000378:metabolism*; D008223:Lymphoma; D051379:Mice; D012333:RNA, Messenger / Q000032:analysis* / Q000235:genetics; D014158:Transcription, Genetic
chemical_list: D004274:DNA, Recombinant; D007143:Immunoglobulin Heavy Chains; D007148:Immunoglobulin mu-Chains; D012333:RNA, Messenger